Merge branch 'dev' into gpio-reset-pulse

Call sites read as pulse_reset(pin, {.high_before_ms = 1, .low_ms = 10}) instead of bare
positional numbers. The inline wrapper passes the fields in registers, so the build is
byte identical to the positional form.

esphome/core/gpio.cpp

@@ -1,4 +1,5 @@
 #include "esphome/core/gpio.h"
+#include "esphome/core/hal.h"
 #include "esphome/core/log.h"
 
 namespace esphome {
@@ -18,4 +19,18 @@ void log_pin(const char *tag, const char *prefix, GPIOPin *pin) {
 }
 #endif
 
+namespace internal {
+void pulse_reset_ms(GPIOPin *pin, uint32_t high_before_ms, uint32_t low_ms, uint32_t high_after_ms) {
+  if (pin == nullptr)
+    return;
+  pin->setup();
+  const uint32_t waits[] = {high_before_ms, low_ms, high_after_ms};
+  // Level for each step is high, low, high; a zero high_before_ms skips the first step
+  for (size_t i = high_before_ms == 0; i < 3; i++) {
+    pin->digital_write(i != 1);
+    delay(waits[i]);
+  }
+}
+}  // namespace internal
+
 }  // namespace esphome

esphome/core/gpio_pin.h

@@ -144,4 +144,24 @@ void log_pin(const char *tag, const __FlashStringHelper *prefix, GPIOPin *pin);
 void log_pin(const char *tag, const char *prefix, GPIOPin *pin);
 #endif
 
+/// Waveform for pulse_reset(): high, low, then high again. Name the fields at the call site, e.g.
+/// pulse_reset(this->reset_pin_, {.high_before_ms = 1, .low_ms = 10}).
+struct ResetPulse {
+  uint32_t high_before_ms{0};  ///< Drive high this long first; skipped when 0
+  uint32_t low_ms{0};          ///< Hold the pin low (in reset) this long
+  uint32_t high_after_ms{0};   ///< Wait this long after releasing the pin
+};
+
+namespace internal {
+/// Out-of-line body of pulse_reset(); call that instead.
+void pulse_reset_ms(GPIOPin *pin, uint32_t high_before_ms, uint32_t low_ms, uint32_t high_after_ms);
+}  // namespace internal
+
+/// Set up an active-low reset pin and drive it through \p pulse. Blocks for the whole sequence;
+/// does nothing when pin is null. Inline so the fields reach pulse_reset_ms() in registers
+/// (RISC-V would otherwise pass the struct by reference).
+ESPHOME_ALWAYS_INLINE inline void pulse_reset(GPIOPin *pin, ResetPulse pulse) {
+  internal::pulse_reset_ms(pin, pulse.high_before_ms, pulse.low_ms, pulse.high_after_ms);
+}
+
 }  // namespace esphome

tests/components/core/test_pulse_reset.cpp

@@ -0,0 +1,51 @@
+#include <gtest/gtest.h>
+
+#include <string>
+#include <vector>
+
+#include "esphome/core/gpio.h"
+#include "esphome/core/hal.h"
+
+namespace esphome::core::testing {
+
+class RecordingPin : public GPIOPin {
+ public:
+  void setup() override { this->events += 'S'; }
+  void pin_mode(gpio::Flags /*flags*/) override {}
+  gpio::Flags get_flags() const override { return gpio::FLAG_OUTPUT; }
+  bool digital_read() override { return false; }
+  void digital_write(bool value) override {
+    this->events += value ? 'H' : 'L';
+    this->write_ms.push_back(millis());
+  }
+
+  std::string events;
+  std::vector<uint32_t> write_ms;
+};
+
+TEST(PulseReset, NullPinIsIgnored) { pulse_reset(nullptr, {.low_ms = 1}); }
+
+TEST(PulseReset, LowThenHigh) {
+  RecordingPin pin;
+  pulse_reset(&pin, {.low_ms = 1});
+  EXPECT_EQ(pin.events, "SLH");
+}
+
+TEST(PulseReset, PreHighDrivesHighFirst) {
+  RecordingPin pin;
+  pulse_reset(&pin, {.high_before_ms = 1, .low_ms = 1, .high_after_ms = 1});
+  EXPECT_EQ(pin.events, "SHLH");
+}
+
+// Distinct waits, so dropping or swapping one shows up; only lower bounds, a busy host can run long
+TEST(PulseReset, HoldsEachLevelForItsTime) {
+  RecordingPin pin;
+  pulse_reset(&pin, {.high_before_ms = 10, .low_ms = 20, .high_after_ms = 30});
+  const uint32_t end = millis();
+  ASSERT_EQ(pin.events, "SHLH");
+  EXPECT_GE(pin.write_ms[1] - pin.write_ms[0], 10u);
+  EXPECT_GE(pin.write_ms[2] - pin.write_ms[1], 20u);
+  EXPECT_GE(end - pin.write_ms[2], 30u);
+}
+
+}  // namespace esphome::core::testing